The present invention has for an object an agent for the coloring of keratin fibers, for example silk, wool or hair and particularly human hair, based on oxidative dyes and containing at least one heterocyclic hydrazone derivative (of the thiazole or oxazole family) as developer and at least one persulfate salt as oxidant, a multicomponent kit and a method for the coloring of keratin fibers by use of said agent.
Hair colorants are divided mainly into the groups of oxidative colorants or of tinting agents, depending on the initial color of the hair to be dyed and on the end result desired. Oxidative colorants are eminently suited for covering larger gray portions. The oxidative colorants used for an up to 50% portion of gray hair are as a rule referred to as oxidative tinting agents, whereas the oxidative colorants used for a greater than 50% portion of gray hair or for “brightening” are usually referred to as oxidative dyes. Direct dyes are contained mainly in non-oxidative colorants (known as tinting agents). Because of their small [molecular] size, some direct dyes, for example the nitro dyes, can penetrate into the hair and dye the hair directly, at least in the outer regions. Such tinting agents are very gentle to the hair and, as a rule, withstand 6 to 8 hair washes. Direct dyes are also often used in oxidative colorants to create certain shades or for color intensification. The previously known colorant systems, however, cannot meet in every respect the requirements placed on colorants, particularly in terms of luster and color intensity.
Surprisingly, we have now found that heterocyclic hydrazones of the thiazole or oxazole family give with common couplers, for example aromatic hydroxyl and/or amino groups-containing compounds, in the presence of persulfate salts intense colorations in the yellow to blue color range. These novel colorants give unusually brilliant and intense colorations showing very high perspiration resistance.